<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
	function cal(op){
					let number1 = document.getElementById("number1").value
					let number2 = document.getElementById("number2").value
					let number3 = eval(number1+op+number3)
					if(isNaN(number3)|| !isFinite(number3)){
						document.getElementById("number3").value="只能输入数字进行计算,且除数不为0"
						return;
					}
					document.getElementById("number3").value = number3.toFixed(15)-0
				}
			</script>
		</head>
		<body>
			第一个数：<input type="text" id="number1" /><br>
			第二个数：<input type="text" id="number2" /><br>
			<button onclick="cal('+')">+</button>
			<button onclick="cal('-')">-</button>
			<button onclick="cal('*')">*</button>
			<button onclick="cal('/')">/</button><br>
			计算结果：<input type="text" id="number3" /><br>
		</body>
	</html>
